An SMS sent from a mobile handset to an application is referred to as an MO message. The term describes the process and flow of a handset sending a short message submission to its home network SMSC utilizing the mo-ForwardSM transaction, which will store and forward to the destination mobile number or short code. In the case of a short code or A2P long number, the SMSC will pass the message to the aggregator, and the aggregator will pass it onto the enterprise who has leased that number. An acknowledgement (delivery notification) is also sent back to the originating handset once the message is delivered to the enterprise.
